Well, on the HiRISE web page it is described innocuously as "Candidate Cavern Entrance Northeast of Arsia Mons" - and that's what it is supposed to be: a round hole with a diameter of about 100 meter in the ceiling of a wide cavern in the Martian ground. It's so deep that the sun, at 03:27 PM local Martian time at about 38 degrees above the horizon, doesn't reach the ground. You should have a look at this detailed photo...

Similar geological features (even with about the same diameter) exist also on Earth - for example the Zacaton sinkholes in Mexico. On Earth, these caverns are filled with water (see here for a detailed description as PDF file). The satellite images from the hole on Mars are now better than those of Zacaton at google.maps - that's crazy...

UPDATE (September 7, 2007):New photos, also taken by the HiRISE collaboration, show the shadow of the rim cast onto the wall of the pit. The photo allows to calculate that the pit is at least 78 meters (255 feet) deep, and the new data suggest that the hole has volcanic origins.

19 comments:

weird! at first glimpse I thought the photo is contemporary art. can one measure the temperature of the black body radiation and find out something about the cavern (i.e. if the Martians live in there?) Best, B.

If you look in detail at Emily Lakdawalla's Planetary Society weblog, there are several of these 'holes', and they are all relatively close to each other (they are all nearby in lat. & long.). Weird! I'd like to go explore that; who know what one will find down there!

OK, let's stay with both feet firmly on the ground of reason and common sence.

1)it is a cavern.2) what made it cave in? (where is the displaced material)3)how stable are the outer edges, (is it safe to get near?)4) is this the best location to search for water on Mars?

The seatch for water should be the only reason for spending (half a day's Irak-war worth of)money to explore further.

As it is a round hole, I find that the near terrain in a short distance from the hole has probably the same geologic features as the very spot which has now caved in to become the hole (cavern).

to seatch for water it would therefore be wiser to do exploration say a couble of hundres meters avay from the edge.

If we were to explore the cavern itself a baloon could be anchored by winches in a star-like pattern, and exploration equipment could be lowered down without the risk of provoking catastrophic instability of the edges.

It seems, that the edges have an "overhang" so the cavity should be greater by volume than can be immediately estimated from the size of the spot.

If we are lucky, we will find that water has simply undermined the surface.

Just hope Smolin's Cosmic Selection is quickly proven wrong, otherwise this black hole could very well spawn offspring. ;-) And before we know it, there'll be baby black holes invading planet Earth!

Thus, our only hope for survival would be to devise a weapon containing eternal inflation. So then we can aim this high-powered weapon at these black holes of Martian descent blasting them out of the Solar System, out of the Milky Way, and ultimately out of the Universe!

The only way I can see to make something like this is to (a) have an ocean of water, (b) have it freeze, (c) have it covered with dirt, perhaps from a volcano, and then (d) have part of it remove its protective cover and begin to sublimate away.

Of course it's been caused by global warming on Mars. ;-) I just heard about NASA (I think?) testing a deep diving device for future use in exploring Europa, and I'm pretty sure they are testing it in the Mexican sinkhole.

If you look in detail at Emily Lakdawalla's Planetary Society weblog, there are several of these 'holes'

yes, indeed - and interestingly, the Zacaton sinkhole is also only one hole of a whole system of caverns - you can see them on the satellite photos at maps.google as round dark spots.

However, if I understand that correctly, these caverns in Mexico are typical Karst phenomena, which means that the dissolution of limestone by carbonated water is essential for their formation.

I am not sure which mechanisms have created these caverns and voids below the Martian surface. Karst formation requires lots of water, and I imagine that there is not enough available on Mars (...although it may be possible that if there is still water left, it may be in these holes)

From the references in the paper that Carl has mentioned, I have the impression that one thinks that the origin of the voids may be tectonic, similar to rift valley phenomena - see e.g. here.

They're on the side of a volcano so they're almost certainly lava tubes that form when lava empties out of a lava flow.

Thank you for that hint - so this may also be an option!

BTW, the photo at the Astronomy Picture of the Day seems to be the same that we have here - cut differently, an with a slightliy different shade...

I just heard about NASA (I think?) testing a deep diving device for future use in exploring Europa, and I'm pretty sure they are testing it in the Mexican sinkhole.

Exaclty - by some funny coincidence, the same edition of the FAZ that had the article about the "black hole" reported also this experiment at the Zacaton sinkhole.. That's how I learned about it ;-). This diving devive is called DEPTHX, and you can find more information at this page at the University of Texas.

Stefan, as it turns out, my day job involves getting environmental permits in order for a biofuel plant. One of the things I had to write up yesterday was a description of the hydrology of the site. Turns out that it's on basalt which is, sure enough, run through with lava tubes through which water moves very well.

Of course one can see details in that black hole, if you have ACDSee on your computer take a look at the "detailed picture" in the beginning of the article and use the "embossing" function, then look at the right picture. It definitively shows, in relief, details. Now it looks like a crater with ripples in some nonreflecting material at the bottom. My guess would be ice mixed with black volcanic dust..